Formation of hybrid polyanion/metal cation/anionic surfactant films via interface complexation and Langmuir–Blodgett technique

We demonstrate that highly-ordered supramolecular polyanion/polyvalent metal cation/anionic amphiphile complex ultrathin multilayer superlattice films with separating acidic amphiphile bilayers by highly rare-earth-doped hydrophilic polymeric interlayers can be fabricated using Langmuir–Blodgett technique along with interface ligand exchange and coordination reactions. The properties of stearic acid (SA) Langmuir monolayer on the aqueous subphase containing Gd acetate and polysterene sulfonate (PSS)-Na were studied and PSS-Gd-SA multilayer films were deposited successfully onto the solid substrates by conventional vertical dipping method. Built-up films were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction and atomic force microscopy (AFM). FTIR spectroscopy analysis of multilayer films showed high degree of amphiphile and polyanion acidic groups ionization under complexation with rare-earth cations. AFM study of surface morphology of the built-up films revealed unique structure of PSS-Gd-SA film different from polymeric Gd-PSS polymeric complex film and gadolinium stearate Langmuir–Blodgett film. The data obtained give evidence for the formation of high-quality superlattice structures PSS-Gd-SA hybrid films with stearate bilayers separated by Gd-PSS complex interlayers of ∼0.5 nm thickness.